Adaptive response of rat pancreatic lipase to dietary fat: effects of amount and type of fat.

Pancreatic lipase adapts to changes in dietary fat by parallel changes in synthesis. The adaptation to changes in type of dietary fat (saturation or chain length) is unclear. The effects of changes in amount and type of dietary fat were examined in weanling rats fed for 1 wk diets low in fat (LF) with 10% kcal as corn oil, moderate in fat (MF) with 40% kcal as fat (corn oil, lard, safflower oil, butter, olive oil or coconut oil), or high in fat (HF) with 67% kcal as fat (as for MF). Growth was comparable among rats fed these diets. Pancreatic lipase activity increased in all HF diets (180%) compared to the LF diet. In MF diets, only the highly unsaturated safflower oil increased pancreatic lipase (162%) compared to the LF diet. Food consumption varied, but was not related to the response of pancreatic lipase. When weanling rats were fed diets with 11, 40, 47, 54, 67 and 75% kcal as corn oil, pancreatic lipase activity was not stimulated at or below 47% kcal fat, but was maximally stimulated (twofold) by 54 or 67% fat. These findings suggest that pancreatic lipase activity adapts primarily to the amount of dietary fat and responds to the type of fat only below the threshold level of dietary fat (47% kcal).